Preprints
https://doi.org/10.5194/tc-2022-14
https://doi.org/10.5194/tc-2022-14
 
17 Feb 2022
17 Feb 2022
Status: this preprint is currently under review for the journal TC.

Halving of Swiss glacier volume since 1931 observed from terrestrial image photogrammetry

Erik Schytt Mannerfelt1,2, Amaury Dehecq1,2,3, Romain Hugonnet1,2,4, Elias Hodel1,2, Matthias Huss1,2,5, Andreas Bauder1,2, and Daniel Farinotti1,2 Erik Schytt Mannerfelt et al.
  • 1Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich, Zurich, Switzerland
  • 2Switzerland Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Birmensdorf, Switzerland
  • 3Univ. Grenoble Alpes, CNRS, IRD, Grenoble INP, IGE, Grenoble, France
  • 4LEGOS, Université de Toulouse, CNES, CNRS, IRD, UPS, F-31400 Toulouse, France
  • 5Department of Geosciences, University of Fribourg, Fribourg, Switzerland

Abstract. The monitoring of glaciers in Switzerland has a long tradition, yet glacier changes during the 20th century are only known through sparse observations. Here, we estimate a halving of Swiss glacier volumes between 1931 and 2016 by mapping historical glacier elevation changes at high resolution. Our analysis relies on a terrestrial image archive known as TerrA, which covers about 86 % of the Swiss glacierised area with 21,703 images acquired during the period 1916–1947 (1931 on average). We developed a semi-automated workflow to generate digital elevation models (DEMs) from these images, resulting in a 45 % total glacier coverage. Using the geodetic method, we estimate a Swiss-wide glacier mass balance of –0.52 ± 0.09 m w.e. a−1 between 1931 and 2016. This equates to a 51.5 ± 6.1 % loss in glacier volume. We find that low elevation, high debris cover, and gently sloping glacier termini are conductive to particularly high mass losses. In addition to these glacier-specific, quasi- centennial elevation changes, we present a new inventory of glacier outlines with known timestamps and complete attributes from around 1931. The fragmented spatial coverage and temporal heterogeneity of the TerrA archive are the largest sources of uncertainty in our glacier-specific estimates, reaching up to 0.50 m w.e. a−1. We suggest that the high-resolution mapping of historic surface elevations could unlock great potentials also for research fields other than glaciology.

Erik Schytt Mannerfelt et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on tc-2022-14', Thorsten Seehaus, 18 Feb 2022
    • AC1: 'Reply on CC1', Erik Mannerfelt, 23 Jun 2022
  • RC1: 'Comment on tc-2022-14', Anonymous Referee #1, 21 Feb 2022
    • AC2: 'Reply on RC1', Erik Mannerfelt, 23 Jun 2022
  • RC2: 'Comment on tc-2022-14', Anonymous Referee #2, 04 Apr 2022
    • AC3: 'Reply on RC2', Erik Mannerfelt, 23 Jun 2022
  • RC3: 'Comment on tc-2022-14', Anonymous Referee #3, 27 May 2022
    • AC4: 'Reply on RC3', Erik Mannerfelt, 23 Jun 2022

Erik Schytt Mannerfelt et al.

Erik Schytt Mannerfelt et al.

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Latest update: 30 Jun 2022
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Short summary
How glaciers respond to climate change is well-known over the last 20 years, but earlier data are much more scarce. We change this in Swizerland by using 22,000 photographs taken from mountain-tops between the first and second world wars, and find a halving of Swiss glacier volume since 1931. This was done through new automated processing techniques that we created. The data are interesting for more than just glaciers, such as mapping forest changes, landslides, and human impacts on the terrain.